Embodiments of the present disclosure generally relate to measuring cardiac motion, and more particularly to measuring cardiac motion using a cardiovascular navigation system.
A prevailing theory regarding response to cardiac resynchronization therapy (CRT) is that the therapy corrects mechanical dyssynchrony of the heart. Therefore, methods and systems have been proposed to accurately assess the dyssynchrony. The dyssynchrony information may be used to predict response to CRT as well as optimize LV lead placement and CRT programming parameters. Today, most methods to assess mechanical dyssynchrony involve echocardiography. However, in certain circumstances, conventional echocardiography techniques may experience errors that lead to inaccurate characterization of dyssynchrony. Further, questions still remain as to which specific approach(es) is(are) preferred for assessing dyssynchrony, with various indices being used with mixed success.
Today, various cardiovascular navigation systems exist. For example, the St. Jude Medical MediGuide™ (MDG) cardiovascular navigation system is a 3-D electromagnetic navigation system that provides real-time position and orientation information of sensors embedded in electrophysiologic tools. The MDG system is integrated with a fluoroscopic (or other diagnostic) imaging system and tracks the sensors continuously within an imaging volume defined by the fluoroscopic system, on both live and pre-recorded background diagnostic images.
Recently, it has been proposed to utilize the MDG system to characterize motion of the heart and to identify a desired (e.g., optimal) location for placement of a left ventricular (LV) lead for CRT. For example, the MDG system systematically records information associated with various endocardial and epicardial locations in the LV. Depending on the size of the heart and other factors during the procedure, there may be a multitude of locations at which the MDG system obtains motion recordings for each patient. These recordings then need to be analyzed to characterize motion and mechanical activation patterns in the LV.
However, cardiovascular navigation systems may experience inconsistencies in motion characterizations of the heart due to ectopic beats or catheter dislodgments. Ectopic beats and catheter dislodgement create electrical and/or mechanical measurement disturbances that in the measured signals are exhibited as inconsistent electrical rhythm and/or mechanical behavior. Cardiac events occurring during inconsistent electrical rhythm and/or mechanical behavior may exhibit unreliable motion characterization information. Methods and systems are needed to identify and filter out ectopic beats or beats occurring during catheter dislodgement such that the remaining beats exhibit consistent motion information that yields reliable motion characterization.